Live $1/2 PLO, deep stacked.
I limp call early position with
3

6

7

9
(three mega fish at the table, I wanted to get into as many pots with them as possible since it was a race to get their stacks, they would call often to the river with mediocre hands like bottom sets and 3 pair and sometimes call the river bets too). We see a flop for $10 each (we round up the first raise in that game from $7 to $10) seven handed.
Flop is 4

5

K

.
Blinds check, I lead out for pot ($80). Girl who is an aggressive player immediately repots it to $320 behind me. I have about $1400 behind and she has me covered. Shortie on the button (older guy, doesn't strike me as particularly good, has called the river and mucked face down on several occasions already, and is not very aggressive) has exactly $320 and calls and everyone has folded to me.
Given my reads on the girl, I know right away that she has KKxx. There hasn't been very much 3Bing at the table (only AAxx) so I have no idea how good the KKxx hand is, BUT the K

is still out there. Just from my (limited) reads, it seemed like she really really wanted me to fold, so I put a little more weight into the fact that she probably had just a bare set of Kings and was worried about draws hitting.
Since the other man hadn't really shown down many hands, it was hard to put him on a set or flush draw or combo draw (or much of anything since he had folded the river so often).
Any thoughts on my flop action?
I decided to just flat the extra $240 and see a turn with a main pot of $1040 and no side pot. I have just over a PSB left and I'm OOP.
My normal line here if just HU would be to flat the flop raise and call/shove any blank non-pairing turn.... but does the presence of the third AI player and a dry side pot influence my play? My read on the shortie's hand range is pretty wide (I assume he's not very good) and could include a higher flush draw, set, etc.